System and method for heating feed water through reheated steam to achieve deep peak regulation

Abstract

The invention discloses a system and method for heating feed water through reheat steam to achieve deep peak regulation. According to the system and method, a steam-steam heat exchanger serves as a full-load-section operation system, steam behind a rear screen is used for heating cold reheat steam, the reheat steam is used for heating the feed water, and low-pressure steam heated through the rear screen is extracted for heating a primary air pulverized coal pipeline. When the system runs, reheated steam is pumped to heat feed water through the steam-water heat exchanger, the temperature of the feed water and the wall temperature of the water cooling wall are increased, and the combustion condition of the boiler is improved; after the cooled steam absorbs heat in the steam-steam heater, part of the cooled steam is pumped out to heat primary air pulverized coal airflow, the initial temperature of the pulverized coal airflow is increased, and the ignition and stable combustion performance of the boiler is improved; heat of the superheater is guided out through the steam-steam-water heat exchanger, part of heat of superheated steam and reheated steam is used for increasing the feed water temperature and the primary air pulverized coal airflow temperature, and the effects that the low-load ignition stability is improved, the load point for converting the boiler into the wet state is increased, the deep adjustment load of the boiler is reduced, and the unit operation flexibility is improved are achieved.

Description

technical field [0001] The invention belongs to the technical field of comprehensive transformation of deep peak regulation flexible operation of power station boilers, and relates to a system and method for using reheated steam to heat feed water to realize deep peak regulation. Background technique [0002] Large thermal power units, especially ultra (super) critical thermal power units, participate in wide-load deep peak regulation, so that the boilers and related main and auxiliary equipment of the unit are often under conditions of low load and large load change rate, and the unit is required to have a lower load. load limit. This extremely low load operation demand and large load change rate directly affect the safety and economy of the unit, and may cause the following problems: [0003] 1) The combustion stability of the boiler is poor, and the safety and economy of the system operation is reduced. The minimum stable combustion load design value of large thermal po...

AI Technical Summary

Problems solved by technology

During deep peak-shaving operation, the combustion condition of the boiler is lower than the minimum stable combustion load originally designed, the temperature level of the furnace drops sharply, and the stability of pulverized coal ignition is poor, and there is a major hidden danger of furnace fire extinguishing

When the boiler is operated under the condition of starting and stopping the boiler and extremely low load, the boiler needs to be fed with oil to support the combustion, and the pulverized coal will be ignited and burned out, which may cause accidents such as secondary combustion at the tail, deflagration of electric dust removal, and poisoning of desulfurization slurry. The long-term operation of the system is safe and economical. Significantly lower sex

[0004] 2) The deviation of the flue temperature and the wall temperature of the water wall and the heating surface increases, the hydrodynamic safety decreases, and the main reheating steam temperature is insufficient

However, there is a serious problem in this technology, that is, the valves for high-pressure steam extraction control generally need to be imported. Even if the imported valves operate frequently, the failure rate is very high, which leads to a great safety risk of the system. Therefore, the practicability of the scheme Not strong

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